Forms of rifaximin and uses thereof

ABSTRACT

The present invention relates to Rifaximin polymorphic forms, to their use in medicinal preparations and to therapeutic methods using them.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.12/393,012, filed Feb. 25, 2009, which claims the benefit of U.S.Provisional Application No. 61/031,329, filed Feb. 25, 2008. The entirecontents of each of the aforementioned application is hereby expresslyincorporated herein by reference.

BACKGROUND

Rifaximin (INN; see The Merck Index, XIII Ed., 8304) is an antibioticbelonging to the rifamycin class of antibiotics, e.g., a pyrido-imidazorifamycin. Rifaximin exerts its broad antibacterial activity, forexample, in the gastrointestinal tract against localizedgastrointestinal bacteria that cause infectious diarrhea, irritablebowel syndrome, small intestinal bacterial overgrowth, Crohn's disease,and/or pancreatic insufficiency. It has been reported that rifaximin ischaracterized by a negligible systemic absorption, due to its chemicaland physical characteristics (Descombe J. J. et al. Pharmacokineticstudy of rifaximin after oral administration in healthy volunteers. IntJ Clin Pharmacol Res, 14 (2), 51-56, (1994)).

Rifaximin is described in Italian Patent IT 1154655 and EP 0161534, bothof which are incorporated herein by reference in their entirety for allpurposes. EP 0161534 discloses a process for rifaximin production usingrifamycin O as the starting material (The Merck Index, XIII Ed., 8301).U.S. Pat. No. 7,045,620 B1 and PCT Publication WO 2006/094662 A1disclose polymorphic forms of rifaximin.

Rifaximin is approved for the treatment of pathologies caused bynon-invasive strains of Escherichia coli, a micro-organism which is notable to penetrate into GI mucosa and therefore remains in contact withgastrointestinal fluids.

SUMMARY

Described herein are polymorphic forms of rifaximin, including Zeta (ζ),Eta (η), Iota (ι), Form Iota-dry (ι-dry), Form Iota-dry′ (ι-dry′), andForm B of rifaximin are described herein.

According to one aspect, polymorphic Form ζ, Form η, Form ι, Form ι-dry,Form ι-dry′, or Form B of rifaximin are presented herein.

In one embodiment, polymorph Form ζ exhibits an X-ray powder diffractionpattern having characteristic peaks expressed in degrees 2θ (+/−0.20degree θ) comprising 4.69, 7.63, 12.52, 13.87.

In one embodiment, polymorph Form ζ of rifaximin comprises an XRPDpattern as substantially depicted in FIG. 4 or FIG. 15 wherein peaks inthe XRPD patterns have a variation of +/−0.2 theta.

In one embodiment, polymorph Form ζ exhibits an X-ray powder diffractionpattern having characteristic peaks expressed in degrees 2θ (+/−0.20degree θ) comprising 6.1, 7.3, and 7.5 degrees 2-θ; or 6.1, 7.3, and 7.9degrees 2-θ; 5.3, 6.1, 7.3, 7.5, 8.8, and 12.7 degrees 2-θ; or 5.3, 6.1,7.3, 7.9, 8.8, and 12.7 degrees 2-θ; or 5.3, 6.1, 7.3, 7.5, 7.9, 8.8,12.7 degrees 2-θ; or 6.1, 7.3, 7.5, 7.9, 8.8, and 12.7 degrees 2-θ.

In one embodiment, polymorph Form ι exhibits an X-ray powder diffractionpattern having characteristic peaks expressed in degrees 2θ (+/−0.20degree θ) comprising 5.49, 5.88, 7.86, 9.03, 12.66, and 13.89.

In one embodiment, Form ι exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)comprising 5.9; 7.9; 9.0; or 12.7; 13.9; 14.9; or 5.9; 7.9; 12.7; or5.9; 9.0; 12.7; or 5.9; 13.9; 14.9; or 5.9; 7.9; 14.9; or 9.0; 12.7;14.9; or 5.9; 7.9; 9.0; 14.9; or 5.9; 7.9; 9.0; 12.7; or 5.9; 7.9; 9.0;12.7; 13.9; 14.9.

In one embodiment, polymorph Form ι of rifaximin comprises an XRPDpattern as substantially depicted in FIG. 3 or FIG. 9 wherein peaks inthe XRPD patterns have a variation of +/−0.2 theta.

In one embodiment, polymorph Form ι of rifaximin compromises thermaldata as substantially depicted in FIG. 10 or proton NMR spectrum assubstantially depicted in FIG. 12 or vapor data as substantiallydepicted in FIG. 11 or FT-IR spectrum as substantially depicted in FIG.13.

In one embodiment, Form ι is formulated into a pharmaceuticallyacceptable dosage form.

In one embodiment, From ι-dry exhibits an X-ray powder diffractionpattern having characteristic peaks expressed in degrees 2θ (+/−0.10degree θ) comprising 6.04, 7.90, 8.92, 9.49, 12.76, and 14.14.

In one embodiment, Form ι-dry of rifaximin comprises an XRPD pattern assubstantially depicted in FIG. 1 or FIG. 6 or thermal data assubstantially depicted in FIG. 7.

In one embodiment, polymorph Form ι-dry is formulated into apharmaceutically acceptable dosage form.

In one embodiment, polymorph From ι-dry′ exhibits an X-ray powderdiffraction pattern having characteristic peaks expressed in degrees 2θ(+/−0.15 degree θ) comprising 6.16, 7.92, 8.89, 9.55, 12.80, and 14.25.

In one embodiment, polymorph Form ι-dry′ comprises an XRPD pattern assubstantially depicted in FIG. 2 or FIG. 8 wherein peaks in the XRPDpatterns have a variation of +/−0.15 theta.

In one embodiment, polymorph From ι-dry′ is formulated into apharmaceutically acceptable dosage form.

In one embodiment, polymorph From B exhibits an X-ray powder diffractionpattern having characteristic peaks expressed in degrees 2θ (+/−0.15degree θ) comprising 5.24, 6.84, 7.74, 8.71, 10.16, and 12.21.

In one embodiment, polymorph Form B comprises an XRPD pattern assubstantially depicted in FIG. 6 wherein peaks in the XRPD patterns havea variation of +/−0.15 theta or having DSC or TGA thermograms assubstantially depicted in FIG. 17.

In one embodiment, the polymorphs comprise from between about 50 toabout 100% pure polymorphous forms before or after formulation.

In one embodiment, the polymorphs comprise from between about 75 toabout 100% pure polymorphous forms before or after formulation.

According to one aspect, provided herein are pharmaceutical dosage formscomprising one or more of polymorphic Form ζ, Form η, Form ι, Formι-dry, Form ι-dry′, or Form B of rifaximin or mixtures thereof.

Other embodiment and aspects are disclosed infra.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary XRPD pattern of Form Iota dry.

FIG. 2 is an exemplary XRPD pattern of Form Iota dry′.

FIG. 3 is an exemplary XRPD pattern of Form Iota.

FIG. 4 is an exemplary XRPD pattern of Form Zeta.

FIG. 5 is an exemplary XRPD pattern of Form B (formerly β-1, β-2).

FIG. 6 is an exemplary XRPD pattern of Form Iota dry.

FIG. 7 is an exemplary DSC and TGA thermo grams of rifaximin Form Iotadry.

FIG. 8 is an exemplary XRPD pattern of rifaximin Form Iota dry′.

FIG. 9 is an exemplary XRPD pattern of rifaximin Form Iota.

FIG. 10 shows exemplary DSC and TGA thermo grams of rifaximin Form Iota.

FIG. 11 is an exemplary dynamic vapor sorption/desorption of rifaximinForm Iota.

FIG. 12 is an exemplary proton NMR spectrum of rifaximin Form Iota.

FIG. 13 is an exemplary FT-IR spectrum of rifaximin Form Iota.

FIG. 14 depicts exemplary hot stage images for rifaximin Form t.

FIG. 15 is an exemplary XRPD pattern of rifaximin Form Zeta.

FIG. 16 is an exemplary XRPD pattern of rifaximin Form B.

FIG. 17 shows exemplary DSC and TGA thermograms of rifaximin Form B.

FIG. 18 is an exemplary XRPD pattern of rifaximin Form Eta.

DETAILED DESCRIPTION

Embodiments of the invention relate to the discovery of new polymorphicforms of rifaximin and the use of those forms as antibiotics. In oneembodiment the use of Form ζ, Form η, Form ι, Form Iota-dry, FormIota-dry′ and Form B, of the antibiotic known as Rifaximin (INN), in themanufacture of medicinal preparations for the oral or topical route iscontemplated. Embodiments of the invention also relate to administrationof such medicinal preparations to a subject in need of treatment withantibiotics.

The different forms of Rifaximin described herein can be made by themethods set forth, for example, in the Examples section. Moreover,polymorphic forms of Rifaximin can be converted to one or more otherpolymorphic forms of Rifaximin by subjecting them to conditions such asthose set forth in the examples.

Rifaximin is a compound of the rifamycin class of antibiotics. Rifaximinis a compound having the structure of Formula I:

As used herein, “rifaximin Form ζ,” “Form ζ” “Form ζ of rifaximin,”“polymorph c,” and “rifaximin ζ” are used interchangeably to denote thepolymorphic form of rifaximin as further described herein by, forexample, one or more peaks of an x-ray diffractogram, differentialscanning calorimetry data. Form ζ comprises an x-ray powder diffractionpattern peak positions as described herein and in the Figures andTables. Form ζ may be identified and characterized by one or more ofthese parameters and/or one or more of the peaks or points in theranges.

As used herein, “rifaximin Form η,” “Form η,” “polymorph η,” “Form η ofrifaximin” and “rifaximin η” are used interchangeably to denote thepolymorphic form of rifaximin as further described herein by, forexample, one or more peaks of an x-ray diffractogram (FIG. 18) andmethods of making such form. Form η comprises an x-ray powderdiffraction pattern peak positions as described herein and in theFigures and Tables. Form η may be identified and characterized by one ormore of these parameters and/or one or more of the peaks or points inthe ranges.

As used herein, “rifaximin Form ι,” “Form ι,” “polymorph ι,” “Form ι ofrifaximin” and “rifaximin ι” are used interchangeably to denote thepolymorphic form of rifaximin as further described herein by, forexample, one or more peaks of an x-ray diffractogram, NMR, thermal data,or hot stage microscopy and methods of making such form. Form ιcomprises x-ray powder diffraction pattern peak positions describedherein and in the Figures and Tables. Form may be identified andcharacterized by one or more of these parameters and/or one or more ofthe peaks or points in the ranges.

As used herein, “rifaximin Form ι-dry,” “Form ι-dry,” “polymorph ι-dry,”“Form ι-dry of rifaximin” and “rifaximin ι-dry” are used interchangeablyto denote the polymorphic form of rifaximin as further described hereinby, for example, one or more peaks of an x-ray diffractogram, NMR,thermal data, or hot stage microscopy and methods of making such form.Form ι-dry comprises x-ray powder diffraction pattern peak positionsdescribed herein and in the Figures and Tables. Form ι-dry may beidentified and characterized by one or more of these parameters and/orone or more of the peaks or points in the ranges.

As used herein, “rifaximin Form ι-dry′,” “Form ι-dry′,” “polymorphι-dry′,” “Form ι-dry′ of rifaximin” and “rifaximin ι-dry′” are usedinterchangeably to denote the polymorphic form of rifaximin as furtherdescribed herein by, for example, one or more peaks of an x-raydiffractogram, NMR, thermal data, or hot stage microscopy and methods ofmaking such form. Form ι-dry′ comprises x-ray powder diffraction patternpeak positions described herein and in the Figures. Form ι-dry′ may beidentified and characterized by one or more of these parameters and/orone or more of the peaks or points in the ranges.

As used herein, “rifaximin Form B,” “Form B,” “polymorph B,” “Form B ofrifaximin” and “rifaximin B” are used interchangeably to denote thepolymorphic form of rifaximin as further described herein by, forexample, one or more peaks of an x-ray diffractogram, NMR, thermal data,or hot stage microscopy and methods of making such form. Form Bcomprises x-ray powder diffraction pattern peak positions describedherein and in the Figures. Form B may be identified and characterized byone or more of these parameters and/or one or more of the peaks orpoints in the ranges.

As used herein, the term polymorph is occasionally used as a generalterm in reference to the forms of rifaximin and includes within thecontext, salt, hydrate, polymorph forms of rifaximin disclosed herein.This use depends on context and will be clear to one of skill in theart.

As used herein, the term “about” when used in reference to x-ray powderdiffraction pattern peak positions refers to the inherent variability ofthe peaks depending on, for example, the calibration of the equipmentused, the process used to produce the polymorph, the age of thecrystallized material and the like, depending on the instrumentationused. In this case the measure variability of the instrument was about±0.2 degrees 2-θ. A person skilled in the art, having the benefit ofthis disclosure, would understand the use of “about” in this context.The term “about” in reference to other defined parameters, e.g., watercontent, C_(max), t_(max), AUC, intrinsic dissolution rates,temperature, and time, indicates the inherent variability in, forexample, measuring the parameter or achieving the parameter. A personskilled in the art, having the benefit of this disclosure, wouldunderstand the variability of a parameter as connoted by the use of theword about.

Polymorphism, as used herein, refers to the occurrence of differentcrystalline forms of a single compound in distinct hydrate status, e.g.,a property of some compounds and complexes. Thus, polymorphs aredistinct solids sharing the same molecular formula, yet each polymorphmay have distinct physical properties. Therefore, a single compound maygive rise to a variety of polymorphic forms where each form hasdifferent and distinct physical properties, such as solubility profiles,melting point temperatures, hygroscopicity, particle shape, density,flowability, compactibility and/or x-ray diffraction peaks. Thesolubility of each polymorph may vary, thus, identifying the existenceof pharmaceutical polymorphs is essential for providing pharmaceuticalswith predictable solubility profiles. It is desirable to investigate allsolid state forms of a drug, including all polymorphic forms, and todetermine the stability, dissolution and flow properties of eachpolymorphic form. Polymorphic forms of a compound can be distinguishedin a laboratory by X-ray diffraction spectroscopy and by other methodssuch as, infrared spectrometry. For a general review of polymorphs andthe pharmaceutical applications of polymorphs see G. M. Wall, PharmManuf. 3, 33 (1986); J. K. Haleblian and W. McCrone, J. Pharm. Sci., 58,911 (1969); and J. K. Haleblian, J. Pharm. Sci., 64, 1269 (1975), all ofwhich are incorporated herein by reference.

As used herein, “subject” includes organisms which are capable ofsuffering from a bowel disorder or other disorder treatable by rifaximinor who could otherwise benefit from the administration of a rifaximin asdescribed herein, such as human and non-human animals. Preferred humananimals include human subjects. The term “non-human animals” of theinvention includes all vertebrates, e.g., mammals, e.g., rodents, e.g.,mice, and non-mammals, such as non-human primates, e.g., sheep, dog,cow, chickens, amphibians, reptiles, etc. Susceptible to a boweldisorder is meant to include subjects at risk of developing a boweldisorder infection, i.e., subjects suffering from immune suppression,subjects that have been exposed to other subjects with a bacterialinfection, physicians, nurses, subjects traveling to remote areas knownto harbor bacteria that causes travelers' diarrhea, etc.

The language “a prophylactically effective amount” of a compound refersto an amount of a compound of the invention of formula (I) or otherwisedescribed herein which is effective, upon single or multiple doseadministration to the subject, in preventing or treating a bacterialinfection.

The language “therapeutically effective amount” of a compound of theinvention refers to an amount of an agent which is effective, uponsingle or multiple dose administration to the subject to provide atherapeutic benefit to the subject. In one embodiment, the therapeuticbenefit is inhibiting a virus, or in prolonging the survivability of asubject with such a viral infection. In another embodiment, thetherapeutic benefit is inhibiting a bacterial infection or prolongingthe survival of a subject with such a bacterial infection beyond thatexpected in the absence of such treatment.

Rifaximin exerts a broad antibacterial activity in the gastrointestinaltract against localized gastrointestinal bacteria that cause infectiousdiarrhea, including anaerobic strains. It has been reported thatrifaximin is characterized by a negligible systemic absorption, due toits chemical and physical characteristics (Descombe J. J. et al.Pharmacokinetic study of rifaximin after oral administration in healthyvolunteers. Int J Clin Pharmacol Res, 14 (2), 51-56, (1994)).

In respect to possible adverse events coupled to the therapeutic use ofrifaximin, the induction of bacterial resistance to the antibiotics isof particular relevance.

From this point of view, any differences found in the systemicabsorption of forms of rifaximin may be significant because atsub-inhibitory concentration of rifaximin, such as in the range from 0.1to 1 μg/ml, selection of resistant mutants has been demonstrated to bepossible (Marchese A. et al. In vitro activity of rifaximin,metronidazole and vancomycin against clostridium difficile and the rateof selection of spontaneously resistant mutants against representativeanaerobic and aerobic bacteria, including ammonia producing species.Chemotherapy, 46(4), 253-266, (2000)).

Polymorphs of rifaximin have been found to have differing in vivobioavailability properties. Thus, the polymorphs disclosed herein wouldbe useful in the preparation of pharmaceuticals with differentcharacteristics for the treatment of infections. This would allowgeneration of rifaximin preparations that have significantly differentlevels of adsorption with C_(max) values from about 0.0 ng/ml to 5.0μg/ml. This leads to preparation of rifaximin compositions that are fromnegligibly to significantly adsorbed by subjects undergoing treatment.One embodiment of the invention is modulating the therapeutic action ofrifaximin by selecting the proper polymorphic form, or mixture of forms,for treatment of a patient. For example, in the case of invasivebacteria, the most bioavailable polymorphic form can be selected fromthose disclosed herein, whereas in case of noninvasive pathogens lessadsorbed forms of rifaximin can be selected, since they may be safer forthe subject undergoing treatment.

The above-mentioned novel forms of rifaximin can be advantageously usedas pure and homogeneous products in the manufacture of medicinalpreparations containing rifaximin.

Some features of polymorph Form ζ include, for example:

Form ζ, comprises X-ray powder diffraction pattern having characteristicpeaks expressed degrees 2θ (+/−0.20 degree θ) at 4.69, 7.63, 12.52, and13.87.

Form ζ comprises X-ray powder diffraction pattern having characteristicpeaks expressed degrees 2θ (+/−0.20 degree θ) at 4.69, 7.63, and 12.52.

Form ζ, comprises X-ray powder diffraction pattern having characteristicpeaks expressed degrees 2θ (+/−0.20 degree θ) at 7.63, 12.52, and 13.87.

Form ζ, comprises X-ray powder diffraction pattern having characteristicpeaks expressed degrees 2θ (+/−0.20 degree θ) at 4.69, 12.52, and 13.87.

Form ζ, comprises X-ray powder diffraction pattern having characteristicpeaks expressed degrees 2θ (+/−0.20 degree θ) at 4.69, 7.63, and 13.87.

the polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 4.7(doublet), 7.6 (doublet), and 9.5 degrees 2-θ; or 4.7 (doublet), 7.3,and 8.2 degrees 2-θ; or 7.6 (doublet), 8.6, and 10.5 degrees 2-θ; or8.2, 8.6, and 9.5 degrees 2-θ; or 10.2 (triplet), 12.6 (quintet), and13.2 (doublet) degrees 2-θ; or 7.3, 10.5, and 12.9 (doublet) degrees2-θ; or 7.3, 7.6 (doublet), 8.2, 8.6 degrees 2-θ; or 4.7 (doublet), 7.3,7.6 (doublet), 9.5, and 10.5 degrees 2-θ; or 8.2, 8.6, 9.5, 10.2(triplet), and 10.5 degrees 2-θ; or 8.6, 9.5, 10.2 (triplet), 10.5, and11.2 (doublet) degrees 2-θ; or 4.7 (doublet), 6.3, 6.4, 7.3, 7.6(doublet), 8.2, 8.6, 9.5, 10.2 (triplet), 10.5, 11.2 (doublet), 11.9(doublet), 12.2 (weak), 12.6 (quintet), 12.9 (doublet), 13.2 (doublet)degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 4.7(doublet), 7.6 (doublet), and 9.5 degrees 2-θ; or 4.7 (doublet), 7.3,and 8.2 degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 7.6(doublet), 8.6, and 10.5 degrees 2-θ.

The polymorph Form θ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 8.2,8.6, and 9.5 degrees 2-θ.

The polymorph Form θ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 10.2(triplet), 12.6 (quintet), and 13.2 (doublet) degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 7.3,10.5, and 12.9 (doublet) degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 7.3,7.6 (doublet), 8.2, 8.6 degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 4.7(doublet), 7.3, 7.6 (doublet), 9.5, and 10.5 degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 8.2,8.6, 9.5, 10.2 (triplet), and 10.5 degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 8.6,9.5, 10.2 (triplet), 10.5, and 11.2 (doublet) degrees 2-θ.

The polymorph Form ζ exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 4.7(doublet), 6.3, 6.4, 7.3, 7.6 (doublet), 8.2, 8.6, 9.5, 10.2 (triplet),10.5, 11.2 (doublet), 11.9 (doublet), 12.2 (weak), 12.6 (quintet), 12.9(doublet), 13.2 (doublet) degrees 2-θ.

Some features of polymorph Form η include, for example:

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 6.1,7.3, and 7.5 degrees 2-θ; or 6.1, 7.3, and 7.9 degrees 2-θ; or 6.1, 7.3,and 8.8 degrees 2-θ; or 6.1, 7.3, and 12.7 degrees 2-θ; or 6.1, 7.5, and8.8 degrees 2-θ; or 6.1, 7.5, and 7.9 degrees 2-θ; or 5.3, 6.1, and 7.3degrees 2-θ; or 5.3, 6.1, and 7.9 degrees 2-θ; or 5.3, 6.1, and 12.7degrees 2-θ; or 5.3, 6.1, and 7.5 degrees 2-θ; or 5.3, 6.1, and 8.8degrees 2-θ; or 6.1, 7.3, 7.5, 7.9, 8.8, and 12.7 degrees 2-θ; or 5.3,6.1, 7.3, 7.5, 7.9, 8.8, 12.7 degrees 2-θ; or 5.3, 6.1, 7.3, 7.9, 8.8,and 12.7 degrees 2-θ; or 5.3, 6.1, 7.3, 7.5, 8.8, and 12.7 degrees 2-θ;or 5.3, 6.1, 7.3, 7.5, 7.9, 8.8, and 12.7 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 6.1,7.3, and 7.5 degrees 2-θ; or 6.1, 7.3, and 7.9 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 6.1,7.3, and 8.8 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 6.1,7.3, and 12.7 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 6.1,7.5, and 8.8 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 6.1,7.5, and 7.9 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, and 7.3 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, and 7.9 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, and 12.7 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, and 7.5 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, and 8.8 degrees 2-θ; or 6.1, 7.3, 7.5, 7.9, 8.8, and 12.7 degrees2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, 7.3, 7.5, 7.9, 8.8, 12.7 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, 7.3, 7.9, 8.8, and 12.7 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, 7.3, 7.5, 8.8, and 12.7 degrees 2-θ.

Form η exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.3,6.1, 7.3, 7.5, 7.9, 8.8, and 12.7 degrees 2-θ.

Some features of polymorph Form ι, Form Iota-dry and Iota-dry′ include,for example:

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.49,5.88, 7.86, 9.03, 12.66, and 13.89.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.49,5.88, 7.86, 9.03, and 12.66.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.49,5.88, 7.86, 9.03, and 13.89.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.49,5.88, 9.03, 12.66, and 13.89.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.49,7.86, 9.03, 12.66, and 13.89.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.88,7.86, 9.03, 12.66, and 13.89.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;7.9; 9.0; or 12.7; 13.9; 14.9; or 5.9; 7.9; 12.7; or 5.9; 9.0; 12.7; or5.9; 13.9; 14.9; or 5.9; 7.9; 14.9; or 9.0; 12.7; 14.9; or 5.9; 7.9;9.0; 14.9; or 5.9; 7.9; 9.0; 12.7; or 5.9; 7.9; 9.0; 12.7; 13.9; 14.9.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;7.4; 7.9; 9.4.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 7.4;20.0; 20.9.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;13.9; 14.9.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 20.0;20.9; 23.4.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;13.9; 14.9; 20.0; 20.9.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 7.4;12.7; 13.9; 23.4.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;7.4; 7.9; 12.7; 13.9; 14.9; 20.0; 20.9; 23.4.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;7.4; 7.9; 9.0; 9.4; 12.7; 13.9; 14.9; 20.0; 20.9; 23.4

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;13.9; 14.9; 20.0; 20.9; or 5.9; 13.9; 14.9; or 7.4; 12.7; 13.9; 23.4; or20.0; 20.9; 23.4; or 5.9; 7.4; 7.9; 12.7; 13.9; 14.9; 20.0; 20.9; 23.4;or 5.9; 7.4; 7.9; 9.4; or 7.4; 20.0; 20.9; or 5.9; 7.4; 7.9; 9.0; 9.4;12.7; 13.9; 14.9; 20.0; 20.9; 23.4.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;7.9; 9.0; 12.7; 13.9; 14.9.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;7.9; 9.0.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 12.7;13.9; 14.9.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;7.9; 12.7.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;9.0; 12.7.

The polymorph Form ι exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.9;13.9; 14.9.

The polymorph Form ι-dry exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.04, 7.90, 8.92, 9.49, 12.76, and 14.14.

The polymorph Form ι-dry exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 7.90, 8.92, 9.49, 12.76, and 14.14.

The polymorph Form ι-dry exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.04, 8.92, 9.49, 12.76, and 14.14.

The polymorph Form ι-dry exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.04, 7.90, 9.49, 12.76, and 14.14.

The polymorph Form ι-dry exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.04, 7.90, 8.92, 12.76, and 14.14.

The polymorph Form ι-dry exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.04, 7.90, 8.92, 9.49, and 14.14.

The polymorph Form ι-dry exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.04, 7.90, 8.92, 9.49, and 12.76.

The polymorph Form ι-dry′ exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.16, 7.92, 8.89, 9.55, 12.80, and 14.25.

The polymorph Form ι-dry′ exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 7.92, 8.89, 9.55, 12.80, and 14.25

The polymorph Form ι-dry′ exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.16, 8.89, 9.55, 12.80, and 14.25.

The polymorph Form ι-dry′ exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.16, 7.92, 9.55, 12.80, and 14.25.

The polymorph Form ι-dry′ exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.16, 7.92, 8.89, 12.80, and 14.25

The polymorph Form ι-dry′ exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.16, 7.92, 8.89, 9.55, and 14.25.

The polymorph Form ι-dry′ exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)at 6.16, 7.92, 8.89, 9.55, and 12.80.

Some features of polymorph Form B include, for example:

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.24,6.84, 7.74, 8.71, 10.16, and 12.21.

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 6.84,7.74, 8.71, 10.16, and 12.21.

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.24,7.74, 8.71, 10.16, and 12.21.

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.24,6.84, 8.71, 10.16, and 12.21.

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.24,6.84, 7.74, 10.16, and 12.21.

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.24,6.84, 7.74, 8.71, and 12.21.

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.24,6.84, 7.74, 8.71, and 10.16.

The polymorph Form B exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ) at 5.24,6.84, and 7.74.

In one embodiment, the Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′,or Form B, of rifaximin contain less than 5% by weight total impurities.

In one embodiment, the Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′,or Form B, of rifaximin contain less than 50% by weight totalimpurities.

In one embodiment, the Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′,or Form B, of rifaximin contain less than 20% by weight totalimpurities.

In one embodiment, the Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′,or Form B of rifaximin is at least 50% pure, or at least 75% pure, or atleast 80% pure, or at least 90% pure, or at least 95% pure, or at least98% pure.

According to one embodiment, the pharmaceutical composition comprisesone or more of a Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′, orForm B of rifaximin and a pharmaceutically acceptable carrier.

In one embodiment, the composition further comprises one or morepharmaceutically acceptable excipients. The excipients may be one ormore of a diluting agent, binding agent, lubricating agent,disintegrating agent, coloring agent, flavoring agent or sweeteningagent.

According to one embodiment, the pharmaceutical composition may beformulated as coated or uncoated tablets, hard or soft gelatin capsules,sugar-coated pills, lozenges, wafer sheets, pellets or powders in asealed packet. In a related embodiment, the pharmaceutical compositionmay also be formulated for topical use.

According to another aspect, provided herein are methods of treating,preventing or alleviating a bowel related disorder comprisingadministering to a subject in need thereof an effective amount of one ormore of Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′, and Form B ofrifaximin.

In one embodiment, the subject is suffering from at least one bowelrelated disorder selected from the group consisting of irritable bowelsyndrome, travelers' diarrhea, small intestinal bacterial overgrowth,Crohn's disease, chronic pancreatitis, pancreatic insufficiency,enteritis and colitis.

Provided herein, according to one aspect, are packaged compositionscomprising, a therapeutically effective amount of one or more of a Formζ, Form η, Form ι, Form ι-dry, Form ι-dry′, and Form B of rifaximin anda pharmaceutically acceptable carrier or diluent, wherein thecomposition is formulated for treating a subject suffering from orsusceptible to a bowel disorder, and packaged with instructions to treata subject suffering from or susceptible to a bowel disorder.

In one aspect, a pharmaceutical composition is presented, whichcomprises one or more of Form ζ, Form η, Form ι, Form ι-dry, Formι-dry′, and Form B of rifaximin and a pharmaceutically acceptablecarrier.

In one aspect, a pharmaceutical composition is presented, whichcomprises one or more of Form ζ, Form η, Form ι, Form ι-dry, Formι-dry′, or Form B and one or more of these forms with one or more ofForm alpha, Form beta, Form gamma, Form delta, or Form epsilon, ofrifaximin and a pharmaceutically acceptable carrier.

In one embodiment, the pharmaceutical composition further comprisesexcipients.

According to another embodiment, the excipients are one or more of adiluting agent, binding agent, lubricating agent, disintegrating agent,coloring agent, flavoring agent or sweetening agent.

In another embodiment, the composition is formulated for selected coatedand uncoated tablets, hard and soft gelatin capsules, sugar-coatedpills, lozenges, wafer sheets, pellets and powders in sealed packets.

In one embodiment, the composition is formulated for topical use.

Presented herein, according to one aspect, are methods of treating,preventing, or alleviating a bowel related disorder comprisingadministering to a subject in need thereof a cell infected with a viruswith an effective amount of one or more of a Form ζ, Form η, Form ι,Form ι-dry, Form ι-dry′, and Form B of rifaximin.

According to another embodiment, wherein the bowel related disorder isone or more of irritable bowel syndrome, travelers' diarrhea, smallintestinal bacterial overgrowth, Crohn' s disease, chronic pancreatitis,pancreatic insufficiency, or colitis.

Presented herein, according to one aspect, are methods of assessing theefficacy of a bowel related disorder treatment in a subject, monitoringthe progress of a subject being treated for a bowel related disorder, ora method of selecting a subject for treatment of a bowel disorder,comprising:

determining a pre-treatment level of bacterial overgrowth;

administering a therapeutically effective amount of one or more of aForm ζ, Form η, Form ι, Form ι-dry, Form ι-dry′, and Form B of rifaximinto the subject; and determining a post-treatment level of bacterialovergrowth after an initial period of treatment with the one or more ofForm ζ, Form η, Form ι, Form ι-dry, Form ι-dry′, and Form B ofrifaximin.

In one embodiment, the modulation of the level of bacterial overgrowthindicates efficacy of the treatment.

In another embodiment, a decrease in bacterial overgrowth indicates thatthe treatment is efficacious.

In another embodiment, the modulation of the bacterial overgrowth is anindication that the subject is likely to have a favorable clinicalresponse to the treatment.

Presented herein, according to one aspect, are kits for treating a boweldisorder in a subject, comprising one or more actions for use.

Also presented herein, according to one aspect are packaged compositionscomprising a therapeutically effective amount of one or more of a Formζ, Form η, Form ι, Form ι-dry, Form ι-dry′, and Form B of rifaximin anda pharmaceutically acceptable carrier or diluents, wherein thecomposition is formulated for treating a subject suffering from orsusceptible to a bowel disorder, and packaged with instructions to treata subject suffering from or susceptible to a bowel disorder.

Presented herein, is use of Form ζ of rifaximin as a medicament.

Also presented herein is the use of Form η of rifaximin as a medicament.

Also presented herein is the use of Form ι of rifaximin as a medicament.

Also presented herein is the use of Form ι-dry of rifaximin as amedicament.

Also presented herein is the use of Form ι-dry′ of rifaximin as amedicament.

Also presented herein is the use of Form B of rifaximin as a medicament.

Presented herein, according to another aspect, are processes for theproduction of one or more of a Form ζ, Form η, Form ι, Form ι-dry, Formι-dry′, and Form B of rifaximin.

Methods of Treatment

Provided herein are methods of treating, preventing, or alleviatingbowel related disorders comprising administering to a subject in needthereof an effective amount of one or more of the Forms of rifaximindescribed herein. Bowel related disorders include one or more ofirritable bowel syndrome, diarrhea, microbe associated diarrhea,Clostridium difficile associated diarrhea, travelers' diarrhea, smallintestinal bacterial overgrowth, Crohn's disease, chronic pancreatitis,pancreatic insufficiency, enteritis, colitis, hepatic encephalopathy, orpouchitis.

The length of treatment for a particular bowel disorder will depend inpart on the disorder. For example, travelers' diarrhea may only requiretreatment duration of 12 to about 72 hours, while Crohn' s disease mayrequire treatment durations from about 2 days to 3 months. Dosages ofrifaximin will also vary depending on the diseases state. Proper dosageranges are provided herein infra.

Provided herein are methods of treating or preventing a pathology in asubject suspected of being exposed to a biological warfare agent.

The identification of those subjects who are in need of prophylactictreatment for bowel disorder is well within the ability and knowledge ofone skilled in the art. Certain of the methods for identification ofsubjects which are at risk of developing a bowel disorder which can betreated by the subject method are appreciated in the medical arts, suchas family history, travel history and expected travel plans, thepresence of risk factors associated with the development of that diseasestate in the subject. A clinician skilled in the art can readilyidentify such candidate subjects, by the use of, for example, clinicaltests, physical examination and medical/family/travel history.

A method of assessing the efficacy of the treatment in a subjectincludes determining the pre-treatment level of intestinal bacterialovergrowth by methods well known in the art (e.g., hydrogen breathtesting, biopsy, sampling of the intestinal bacteria, etc.) and thenadministering a therapeutically effective amount of a rifaximinpolymorph to the subject. After an appropriate period of time (e.g.,after an initial period of treatment) from the administration of thecompound, e.g., 2 hours, 4 hours, 8 hours, 12 hours, or 72 hours, thelevel of bacterial overgrowth is determined again. The modulation of thebacterial level indicates efficacy of the treatment. The level ofbacterial overgrowth may be determined periodically throughouttreatment. For example, the bacterial overgrowth may be checked everyfew hours, days or weeks to assess the further efficacy of thetreatment. A decrease in bacterial overgrowth indicates that thetreatment is efficacious. The method described may be used to screen orselect subjects that may benefit from treatment with a rifaximinpolymorph.

In yet another aspect, a method of treating a subject suffering from orsusceptible to a bowel disorder comprises administering to a subject inneed thereof a therapeutically effective amount of a rifaximin polymorphdescribed herein, to thereby treat the subject. Upon identification of asubject suffering from or susceptible to a bowel disorder, for example,IBS, one or more rifaximin polymorphs are administered.

In one aspect, methods of assessing the efficacy of treatment with arifaximin polymorph in a subject comprise determining the pre-treatmentlevel of bacterial overgrowth, administering a therapeutically effectiveamount of a rifaximin polymorph to the subject, and determining thebacterial overgrowth after an initial period of treatment with arifaximin polymorph, wherein the modulation of the bacterial overgrowthindicates efficacy of an anti-bacterial treatment.

Efficacy of a treatment may be measured for example, as reduction ofbacterial overgrowth. Efficacy may also be measured in terms of areduction of symptoms associated with the bowel disorder, astabilization of symptoms, or a cessation of symptoms associated with abowel disorder, for example, a reduction of nausea, bloating, diarrhea,and the like.

In one aspect, methods of monitoring the progress of a subject beingtreated with a rifaximin polymorph comprise determining thepre-treatment level of bacterial overgrowth, administering atherapeutically effective amount of a rifaximin polymorph to thesubject, and determining the bacterial overgrowth after an initialperiod of treatment with a rifaximin polymorph, wherein the modulationof the bacterial overgrowth indicates efficacy of an anti-bacterialtreatment.

Pharmaceutical Preparations

Embodiments also provide pharmaceutical compositions, comprising aneffective amount of a rifaximin polymorph (e.g., Form ζ, Form η, Form ι,Form ι-dry, Form ι-dry′, and Form B) described herein and apharmaceutically acceptable carrier. In a further embodiment, theeffective amount is effective to treat a bacterial infection, e.g.,small intestinal bacterial overgrowth, Crohn' s disease, hepaticencephalopathy, antibiotic associated colitis, and/or diverticulardisease.

For examples of the use of rifaximin to treat Travelers' diarrhea, seeInfante R M, Ericsson C D, Zhi-Dong J, Ke S, Steffen R, Riopel L, Sack DA, DuPont, H L. Enteroaggregative Escherichia coli Diarrhea inTravelers: Response to Rifaximin Therapy. Clinical Gastroenterology andHepatology. 2004; 2:135-138; and Steffen R, M.D., Sack DA, M.D., RiopelL, Ph.D., Zhi-Dong J, Ph.D., Sturchler M, M.D., Ericsson CD, M.D., LoweB, M. Phil., Waiyaki P, Ph.D., White M, Ph.D., DuPont H L, M.D. Therapyof Travelers' Diarrhea With Rifaximin on Various Continents. TheAmerican Journal of Gastroenterology. May 2003, Volume 98, Number 5, allof which are incorporated herein by reference in their entirety.

Embodiments also provide pharmaceutical compositions comprising one ormore of a Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′, and Form B ofrifaximin and a pharmaceutically acceptable carrier. That is,formulations may contain only one polymorph or may contain a mixture ofmore than one polymorph. Mixtures may be selected, for example on thebasis of desired amounts of systemic adsorption, dissolution profile,desired location in the digestive tract to be treated, and the like.Embodiments of the pharmaceutical composition further compriseexcipients, for example, one or more of a diluting agent, binding agent,lubricating agent, disintegrating agent, coloring agent, flavoring agentor sweetening agent. One composition may be formulated for selectedcoated and uncoated tablets, hard and soft gelatin capsules,sugar-coated pills, lozenges, wafer sheets, pellets and powders insealed packet. For example, compositions may be formulated for topicaluse, for example, ointments, pomades, creams, gels and lotions.

In an embodiment, the rifaximin polymorph is administered to the subjectusing a pharmaceutically-acceptable formulation, e.g., apharmaceutically-acceptable formulation that provides sustained deliveryof the rifaximin polymorph to a subject for at least 12 hours, 24 hours,36 hours, 48 hours, one week, two weeks, three weeks, or four weeksafter the pharmaceutically-acceptable formulation is administered to thesubject.

In certain embodiments, these pharmaceutical compositions are suitablefor topical or oral administration to a subject. In other embodiments,as described in detail below, the pharmaceutical compositions of thepresent invention may be specially formulated for administration insolid or liquid form, including those adapted for the following: (1)oral administration, for example, drenches (aqueous or non-aqueoussolutions or suspensions), tablets, boluses, powders, granules, pastes;(2) parenteral administration, for example, by subcutaneous,intramuscular or intravenous injection as, for example, a sterilesolution or suspension; (3) topical application, for example, as acream, ointment or spray applied to the skin; (4) intravaginally orintrarectally, for example, as a pessary, cream or foam; or (5) aerosol,for example, as an aqueous aerosol, liposomal preparation or solidparticles containing the compound.

The phrase “pharmaceutically acceptable” refers to those rifaximinpolymorphs of the present invention, compositions containing suchcompounds, and/or dosage forms which are, within the scope of soundmedical judgment, suitable for use in contact with the tissues of humanbeings and animals without excessive toxicity, irritation, allergicresponse, or other problem or complication, commensurate with areasonable benefit/risk ratio.

The phrase “pharmaceutically-acceptable carrier” includespharmaceutically-acceptable material, composition or vehicle, such as aliquid or solid filler, diluent, excipient, solvent or encapsulatingmaterial, involved in carrying or transporting the subject chemical fromone organ, or portion of the body, to another organ, or portion of thebody. Each carrier is preferably “acceptable” in the sense of beingcompatible with the other ingredients of the formulation and notinjurious to the subject. Some examples of materials which can serve aspharmaceutically-acceptable carriers include: (1) sugars, such aslactose, glucose and sucrose; (2) starches, such as corn starch andpotato starch; (3) cellulose, and its derivatives, such as sodiumcarboxymethyl cellulose, ethyl cellulose and cellulose acetate; (4)powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients,such as cocoa butter and suppository waxes; (9) oils, such as peanutoil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil andsoybean oil; (10) glycols, such as propylene glycol; (11) polyols, suchas glycerin, sorbitol, mannitol and polyethylene glycol; (12) esters,such as ethyl oleate and ethyl laurate; (13) agar; (14) bufferingagents, such as magnesium hydroxide and aluminum hydroxide; (15) alginicacid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer'ssolution; (19) ethyl alcohol; (20) phosphate buffer solutions; and (21)other non-toxic compatible substances employed in pharmaceuticalformulations.

Wetting agents, emulsifiers and lubricants, such as sodium laurylsulfate and magnesium stearate, as well as coloring agents, releaseagents, coating agents, sweetening, flavoring and perfuming agents,preservatives and antioxidants can also be present in the compositions.

Examples of pharmaceutically-acceptable antioxidants include: (1) watersoluble antioxidants, such as ascorbic acid, cysteine hydrochloride,sodium bisulfate, sodium metabisulfite, sodium sulfite and the like; (2)oil-soluble antioxidants, such as ascorbyl palmitate, butylatedhydroxyanisole (BHA), butylated hydroxytoluene (BHT), lecithin, propylgallate, alpha-tocopherol, and the like; and (3) metal chelating agents,such as citric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol,tartaric acid, phosphoric acid, and the like.

Compositions containing a rifaximin forms disclosed herein include thosesuitable for oral, nasal, topical (including buccal and sublingual),rectal, vaginal, aerosol and/or parenteral administration. Thecompositions may conveniently be presented in unit dosage form and maybe prepared by any methods well known in the art of pharmacy. The amountof active ingredient which can be combined with a carrier material toproduce a single dosage form will vary depending upon the host beingtreated, the particular mode of administration. The amount of activeingredient which can be combined with a carrier material to produce asingle dosage form will generally be that amount of the compound whichproduces a therapeutic effect. Generally, out of one hundred %, thisamount will range from about 1% to about ninety-nine % of activeingredient, preferably from about 5% to about 70%, most preferably fromabout 10% to about 30%.

Methods of preparing these compositions include the step of bringinginto association a rifaximin polymorph(s) with the carrier and,optionally, one or more accessory ingredients. In general, theformulations are prepared by uniformly and intimately bringing intoassociation a rifaximin polymorph with liquid carriers, or finelydivided solid carriers, or both, and then, if necessary, shaping theproduct.

Compositions suitable for oral administration may be in the form ofcapsules, cachets, pills, tablets, lozenges (using a flavored basis,usually sucrose and acacia or tragacanth), powders, granules, or as asolution or a suspension in an aqueous or non-aqueous liquid, or as anoil-in-water or water-in-oil liquid emulsion, or as an elixir or syrup,or as pastilles (using an inert base, such as gelatin and glycerin, orsucrose and acacia) and/or as mouth washes and the like, each containinga predetermined amount of a rifaximin polymorph(s) as an activeingredient. A compound may also be administered as a bolus, electuary orpaste.

The Forms disclosed herein can be advantageously used in the productionof medicinal preparations having antibiotic activity, containingrifaximin, for both oral and topical use. The medicinal preparations fororal use will contain rifaximin Forms disclosed herein together with theusual excipients, for example diluting agents such as mannitol, lactoseand sorbitol; binding agents such as starches, gelatines, sugars,cellulose derivatives, natural gums and polyvinylpyrrolidone;lubricating agents such as talc, stearates, hydrogenated vegetable oils,polyethylenglycol and colloidal silicon dioxide; disintegrating agentssuch as starches, celluloses, alginates, gums and reticulated polymers;colouring, flavouring and sweetening agents.

Embodiments of the invention include solid preparations administrable bythe oral route, for instance coated and uncoated tablets, of soft andhard gelatin capsules, sugar-coated pills, lozenges, wafer sheets,pellets and powders in sealed packets or other containers.

Medicinal preparations for topical use can contain rifaximin Formsdescribed herein or other previously described Forms of rifaximintogether with usual excipients, such as white petrolatum, white wax,lanoline and derivatives thereof, stearylic alcohol, propylene glycol,sodium lauryl sulfate, ethers of fatty polyoxyethylene alcohols, estersof fatty polyoxyethylene acids, sorbitan monostearate, glycerylmonostearate, propylene glycol monostearate, polyethylene glycols,methylcellulose, hydroxymethyl propylcellulose, sodiumcarboxymethylcellulose, colloidal aluminium and magnesium silicate,sodium alginate.

Embodiments of the invention relate to all of the topical preparations,for instance ointments, pomades, creams, gels and lotions.

In solid dosage forms of rifaximin for oral administration (capsules,tablets, pills, dragees, powders, granules and the like), the activeingredient is typically mixed with one or morepharmaceutically-acceptable carriers, such as sodium citrate ordicalcium phosphate, and/or any of the following: (1) fillers orextenders, such as starches, lactose, sucrose, glucose, mannitol, and/orsilicic acid; (2) binders, such as, for example, carboxymethylcellulose,alginates, gelatin, polyvinyl pyrrolidone, sucrose and/or acacia; (3)humectants, such as glycerol; (4) disintegrating agents, such asagar-agar, calcium carbonate, potato or tapioca starch, alginic acid,certain silicates, and sodium carbonate; (5) solution retarding agents,such as paraffin; (6) absorption accelerators, such as quaternaryammonium compounds; (7) wetting agents, such as, for example, acetylalcohol and glycerol monostearate; (8) absorbents, such as kaolin andbentonite clay; (9) lubricants, such as talc, calcium stearate,magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate,and mixtures thereof; and (10) colouring agents. In the case ofcapsules, tablets and pills, the pharmaceutical compositions may alsocomprise buffering agents. Solid compositions of a similar type may alsobe employed as fillers in soft and hard-filled gelatin capsules usingsuch excipients as lactose or milk sugars, as well as high molecularweight polyethylene glycols and the like.

A tablet may be made by compression or molding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared usingbinder (for example, gelatin or hydroxypropylmethyl cellulose),lubricant, inert diluent, preservative, disintegrant (for example,sodium starch glycolate or cross-linked sodium carboxymethyl cellulose),surface-active or dispersing agent. Molded tablets may be made bymolding in a suitable machine a mixture of the powdered activeingredient moistened with an inert liquid diluent.

The tablets, and other solid dosage forms of the pharmaceuticalcompositions described herein, such as dragees, capsules, pills andgranules, may optionally be scored or prepared with coatings and shells,such as enteric coatings and other coatings well known in thepharmaceutical-formulating art. They may also be formulated so as toprovide slow or controlled release of the active ingredient thereinusing, for example, hydroxypropylmethyl cellulose in varying proportionsto provide the desired release profile, other polymer matrices,liposomes and/or microspheres. They may be sterilized by, for example,filtration through a bacteria-retaining filter, or by incorporatingsterilizing agents in the form of sterile solid compositions which canbe dissolved in sterile water, or some other sterile injectable mediumimmediately before use. These compositions may also optionally containopacifying agents and may be of a composition that they release theactive ingredient(s) only, or preferentially, in a certain portion ofthe gastrointestinal tract, optionally, in a delayed manner. Examples ofembedding compositions which can be used include polymeric substancesand waxes. The active ingredient can also be in micro-encapsulated form,if appropriate, with one or more of the above-described excipients.

Liquid dosage forms for oral administration of the rifaximinpolymorph(s) include pharmaceutically-acceptable emulsions,microemulsions, solutions, suspensions, syrups and elixirs. In additionto the active ingredient, the liquid dosage forms may contain inertdiluents commonly used in the art, such as, for example, water or othersolvents, solubilizing agents and emulsifiers, such as ethyl alcohol,isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol,benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils (inparticular, cottonseed, groundnut, corn, germ, olive, castor and sesameoils), glycerol, tetrahydrofuryl alcohol, polyethylene glycols and fattyacid esters of sorbitan, and mixtures thereof.

In addition to inert diluents, the oral compositions can includeadjuvants such as wetting agents, emulsifying and suspending agents,sweetening, flavoring, coloring, perfuming and preservative agents.

Suspensions, in addition to the active rifaximin polymorph(s) maycontain suspending agents as, for example, ethoxylated isostearylalcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystallinecellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanth,and mixtures thereof.

Pharmaceutical compositions for rectal or vaginal administration may bepresented as a suppository, which may be prepared by mixing one or morerifaximin polymorph(s) with one or more suitable nonirritatingexcipients or carriers comprising, for example, cocoa butter,polyethylene glycol, a suppository wax or a salicylate, and which issolid at room temperature, but liquid at body temperature and,therefore, will melt in the rectum or vaginal cavity and release theactive agent.

Compositions which are suitable for vaginal administration also includepessaries, tampons, creams, gels, pastes, foams or spray formulationscontaining such carriers as are known in the art to be appropriate.

Dosage forms for the topical or transdermal administration of arifaximin polymorph(s) include powders, sprays, ointments, pastes,creams, lotions, gels, solutions, patches and inhalants. The activerifaximin polymorph(s) may be mixed under sterile conditions with apharmaceutically-acceptable carrier, and with any preservatives,buffers, or propellants which may be required.

Ointments, pastes, creams and gels may contain, in addition to rifaximinpolymorph(s), excipients, such as animal and vegetable fats, oils,waxes, paraffins, starch, tragacanth, cellulose derivatives,polyethylene glycols, silicones, bentonites, silicic acid, talc and zincoxide, or mixtures thereof.

Powders and sprays can contain, in addition to a rifaximin polymorph(s),excipients such as lactose, talc, silicic acid, aluminium hydroxide,calcium silicates and polyamide powder, or mixtures of these substances.Sprays can additionally contain customary propellants, such aschlorofluorohydrocarbons and volatile unsubstituted hydrocarbons, suchas butane and propane.

The rifaximin polymorph(s) can be alternatively administered by aerosol.This is accomplished by preparing an aqueous aerosol, liposomalpreparation or solid particles containing the compound. A non-aqueous(e.g., fluorocarbon propellant) suspension could be used. Sonicnebulizers are preferred because they minimize exposing the agent toshear, which can result in degradation of the compound.

An aqueous aerosol is made, for example, by formulating an aqueoussolution or suspension of the agent together with conventionalpharmaceutically-acceptable carriers and stabilizers. The carriers andstabilizers vary with the requirements of the particular compound, buttypically include non-ionic surfactants (Tweens, Pluronics, orpolyethylene glycol), innocuous proteins like serum albumin, sorbitanesters, oleic acid, lecithin, amino acids such as glycine, buffers,salts, sugars or sugar alcohols. Aerosols generally are prepared fromisotonic solutions.

Transdermal patches have the added advantage of providing controlleddelivery of a rifaximin polymorph(s) to the body. Such dosage forms canbe made by dissolving or dispersing the agent in the proper medium.Absorption enhancers can also be used to increase the flux of the activeingredient across the skin. The rate of such flux can be controlled byeither providing a rate controlling membrane or dispersing the activeingredient in a polymer matrix or gel.

Ophthalmic formulations, eye ointments, powders, solutions and the like,are also contemplated as being within the scope of the invention.

Pharmaceutical compositions suitable for parenteral administration maycomprise one or more rifaximin polymorph(s) in combination with one ormore pharmaceutically-acceptable sterile isotonic aqueous or nonaqueoussolutions, dispersions, suspensions or emulsions, or sterile powderswhich may be reconstituted into sterile injectable solutions ordispersions just prior to use, which may contain antioxidants, buffers,bacteriostats, solutes which render the formulation isotonic with theblood of the intended recipient or suspending or thickening agents.

Examples of suitable aqueous and non-aqueous carriers which may beemployed in the pharmaceutical compositions include water, ethanol,polyols (such as glycerol, propylene glycol, polyethylene glycol, andthe like), and suitable mixtures thereof, vegetable oils, such as oliveoil, and injectable organic esters, such as ethyl oleate. Properfluidity can be maintained, for example, by the use of coatingmaterials, such as lecithin, by the maintenance of the required particlesize in the case of dispersions, and by the use of surfactants.

These compositions may also contain adjuvants such as preservatives,wetting agents, emulsifying agents and dispersing agents. Prevention ofthe action of microorganisms may be ensured by the inclusion of variousantibacterial and antifungal agents, for example, paraben,chlorobutanol, phenol sorbic acid, and the like. It may also bedesirable to include isotonic agents, such as sugars, sodium chloride,and the like into the compositions. In addition, prolonged absorption ofthe injectable pharmaceutical form may be brought about by the inclusionof agents which delay absorption such as aluminum monostearate andgelatin.

In some cases, to prolong the effect of a drug, it is desirable to alterthe absorption of the drug. This may be accomplished by the use of aliquid suspension of crystalline, salt or amorphous material having poorwater solubility. The rate of absorption of the drug may then depend onits rate of dissolution which, in turn, may depend on crystal size andcrystalline form. Alternatively, delayed absorption of a drug form isaccomplished by dissolving or suspending the drug in an oil vehicle.

Injectable depot forms are made by forming microencapsule matrices ofrifaximin polymorph(s) in biodegradable polymers such aspolylactide-polyglycolide. Depending on the ratio of drug to polymer,and the nature of the particular polymer employed, the rate of drugrelease can be controlled. Examples of other biodegradable polymersinclude poly(orthoesters) and poly(anhydrides). Depot injectableformulations are also prepared by entrapping the drug in liposomes ormicroemulsions which are compatible with body tissue.

When the rifaximin polymorph(s) are administered as pharmaceuticals, tohumans and animals, they can be given per se or as a pharmaceuticalcomposition containing, for example, 0.1 to 99.5% (more preferably, 0.5to 90%) of active ingredient in combination with apharmaceutically-acceptable carrier.

Regardless of the route of administration selected, the rifaximinpolymorph(s), which may be used in a suitable hydrated form, and/or thepharmaceutical compositions of the present invention, are formulatedinto pharmaceutically-acceptable dosage forms by methods known to thoseof skill in the art.

Actual dosage levels and time course of administration of the activeingredients in the pharmaceutical compositions may be varied so as toobtain an amount of the active ingredient which is effective to achievethe desired therapeutic response for a particular subject, composition,and mode of administration, without being toxic to the subject. Anexemplary dose range is from 25 to 3000 mg per day.

A preferred dose of the rifaximin polymorph for the present invention isthe maximum that a subject can tolerate without developing serious sideeffects. Preferably, the rifaximin polymorph of the present invention isadministered at a concentration of about 1 mg to about 200 mg perkilogram of body weight, about 10 about 100 mg/kg or about 40 mg about80 mg/kg of body weight. Ranges intermediate to the above-recited valuesare also intended to be part.

In combination therapy treatment, both the compounds of this inventionand the other drug agent(s) are administered to mammals (e.g., humans,male or female) by conventional methods. The agents may be administeredin a single dosage form or in separate dosage forms. Effective amountsof the other therapeutic agents are well known to those skilled in theart. However, it is well within the skilled artisan's purview todetermine the other therapeutic agent's optimal effective-amount range.In one embodiment in which another therapeutic agent is administered toan animal, the effective amount of the compound of this invention isless than its effective amount in case the other therapeutic agent isnot administered. In another embodiment, the effective amount of theconventional agent is less than its effective amount in case thecompound of this invention is not administered. In this way, undesiredside effects associated with high doses of either agent may beminimized. Other potential advantages (including without limitationimproved dosing regimens and/or reduced drug cost) will be apparent tothose skilled in the art.

In various embodiments, the therapies (e.g., prophylactic or therapeuticagents) are administered less than 5 minutes apart, less than 30 minutesapart, 1 hour apart, at about 1 hour apart, at about 1 to about 2 hoursapart, at about 2 hours to about 3 hours apart, at about 3 hours toabout 4 hours apart, at about 4 hours to about 5 hours apart, at about 5hours to about 6 hours apart, at about 6 hours to about 7 hours apart,at about 7 hours to about 8 hours apart, at about 8 hours to about 9hours apart, at about 9 hours to about 10 hours apart, at about 10 hoursto about 11 hours apart, at about 11 hours to about 12 hours apart, atabout 12 hours to 18 hours apart, 18 hours to 24 hours apart, 24 hoursto 36 hours apart, 36 hours to 48 hours apart, 48 hours to 52 hoursapart, 52 hours to 60 hours apart, 60 hours to 72 hours apart, 72 hoursto 84 hours apart, 84 hours to 96 hours apart, or 96 hours to 120 hourspart. In preferred embodiments, two or more therapies are administeredwithin the same subject's visit.

In certain embodiments, one or more compounds and one or more othertherapies (e.g., prophylactic or therapeutic agents) are cyclicallyadministered. Cycling therapy involves the administration of a firsttherapy (e.g., a first prophylactic or therapeutic agent) for a periodof time, followed by the administration of a second therapy (e.g., asecond prophylactic or therapeutic agent) for a period of time,optionally, followed by the administration of a third therapy (e.g.,prophylactic or therapeutic agent) for a period of time and so forth,and repeating this sequential administration, i.e., the cycle in orderto reduce the development of resistance to one of the therapies, toavoid or reduce the side effects of one of the therapies, and/or toimprove the efficacy of the therapies.

In certain embodiments, the administration of the same compounds may berepeated and the administrations may be separated by at least 1 day, 2days, 3 days, 5 days, 10 days, 15 days, 30 days, 45 days, 2 months, 75days, 3 months, or at least 6 months. In other embodiments, theadministration of the same therapy (e.g., prophylactic or therapeuticagent) other than a rifaximin polymorph may be repeated and theadministration may be separated by at least 1 day, 2 days, 3 days, 5days, 10 days, 15 days, 30 days, 45 days, 2 months, 75 days, 3 months,or at least 6 months.

Certain indications may require longer treatment times. For example,travelers' diarrhea treatment may only last from between about 12 hoursto about 72 hours, while a treatment for Crohn's disease may be frombetween about 1 day to about 3 months. A treatment for hepaticencephalopathy may be, for example, for the remainder of the subject'slife span. A treatment for IBS may be intermittent for weeks or monthsat a time or for the remainder of the subject's life.

Article of Manufacture

Another embodiment includes articles of manufacture that comprise, forexample, a container holding a pharmaceutical composition suitable fororal or topical administration of rifaximin in combination with printedlabeling instructions providing a discussion of when a particular dosageform should be administered with food and when it should be taken on anempty stomach. Exemplary dosage forms and administration protocols aredescribed infra. The composition will be contained in any suitablecontainer capable of holding and dispensing the dosage form and whichwill not significantly interact with the composition and will further bein physical relation with the appropriate labeling. The labelinginstructions will be consistent with the methods of treatment asdescribed hereinbefore. The labeling may be associated with thecontainer by any means that maintain a physical proximity of the two, byway of non-limiting example, they may both be contained in a packagingmaterial such as a box or plastic shrink wrap or may be associated withthe instructions being bonded to the container such as with glue thatdoes not obscure the labeling instructions or other bonding or holdingmeans.

Another aspect is an article of manufacture that comprises a containercontaining a pharmaceutical composition comprising rifaximin wherein thecontainer holds preferably rifaximin composition in unit dosage form andis associated with printed labeling instructions advising of thediffering absorption when the pharmaceutical composition is taken withand without food.

Packaged compositions are also provided, and may comprise atherapeutically effective amount of rifaximin. Rifaximin and apharmaceutically acceptable carrier or diluent, wherein the compositionis formulated for treating a subject suffering from or susceptible to abowel disorder, and packaged with instructions to treat a subjectsuffering from or susceptible to a bowel disorder.

Kits are also provided herein, for example, kits for treating a boweldisorder in a subject. The kits may contain, for example, one or more ofa Form of rifaximin and instructions for use. The instructions for usemay contain proscribing information, dosage information, storageinformation, and the like.

Packaged compositions are also provided, and may comprise atherapeutically effective amount of one or more of a polymorph ofrifaximin and a pharmaceutically acceptable carrier or diluent, whereinthe composition is formulated for treating a subject suffering from orsusceptible to a bowel disorder, and packaged with instructions to treata subject suffering from or susceptible to a bowel disorder.

EXAMPLES Characterization of Forms

Some of the hydrated, salt and amorphous forms of rifaximin, werecharacterized by one or more of XRPD, thermal analysis, FT-IR, FT-Raman,¹³C NMR. Dried materials obtained by vacuum drying or heating thehydrates were labeled “dry”. These materials exhibited XRPD patternsthat were shifted or contained one or two additional small peaks whencompared to the undried material.

X-ray powder diffraction (XRPD)

X-ray powder diffraction (XRPD) analyses were performed using an InelXRG-3000 diffractometer equipped with a CPS (Curved Position Sensitive)detector with a 2θ range of 120°. Real time data were collected usingCu—Kα radiation starting at approximately 4° 2θ at a resolution of 0.03°2θ. The tube voltage and amperage were set to 40 kV and 30 mA,respectively. The monochromator slit was set at 5 mm by 160 μm. Thepattern is displayed from 2.5-40° 2θ. Samples were prepared for analysisby packing them into thin-walled glass capillaries. Each capillary wasmounted onto a goniometer head that is motorized to permit spinning ofthe capillary during data acquisition. The samples were analyzed for 300seconds. Instrument calibration was performed using a silicon referencestandard. The experimental XRPD pattern was collected at SSCI, Inc.according to cGMP specifications.

Methods of Preparation

Methods of Preparation for Rifaximin Form Iota-dry (ι-dry)

Rifaximin (0.0960 g) was combined with methanol (300 μL) resulting in aclear red solution. The vial was capped and left at ambient conditions.After one day, a red precipitate consisting of birefringent blades andneedles were noted by optical microscopy. After two days, the whole ofsolution was noted as crystallized. The damp crystals were storedrefrigerated (2-8° C.) for one day prior to XRPD analysis. XRPD analysisindicated Form C.

After one month of refrigerated storage, single crystal structuredetermination of one crystal was identified as rifaximin Form ι-dry. Thebulk sample was not analyzed by XRPD.

Rifaximin (Form ι, quantity unmeasured) was placed in a clean vial andcovered with perforated aluminum foil. The vial was then placed in avacuum oven set at 23° C. at ˜30 mm Hg. After 15 hours the sample wasremoved from the vacuum oven, the vial capped and submitted for XRPDanalysis.

Rifaximin (Form ι) was placed in a vial covered with perforated aluminumfoil. The vial was then placed in a vacuum oven set at 22° C. and ˜30mmHg. After ˜16 hours the sample was removed from the vacuum oven andsubmitted for XRPD analysis.

Rifaximin (7.7 mg) was subjected to dynamic vapor sorption/desorptionanalysis. The sample was not dried prior to analysis. Adsorption anddesorption data were collected over a range from 5 to 95% RH at 10% RHincrements under a nitrogen purge. The equilibrium criterion used foranalysis was less than 0.0100% weight change in 5 minutes with a maximumequilibration time of 3 hours. After analysis, the sample was placed ina clean vial and submitted for XRPD analysis.

FT-IR analysis of the sample was also conducted 4 months later. Thesample was not re-analyzed by XRPD to confirm the form.

Rifaximin (Form ι-dry, quantity unmeasured) was placed in a vacuum ovenset at 23° C. and 8-30 in Hg for 3 days. The sample was packed in aglass capillary and submitted for XRPD.

Rifaximin (quantity unmeasured) was placed in a vacuum oven set at 23°C. and 8-30 in Hg for 3 days. The sample was packed in a glass capillaryand submitted for XRPD. Form ι-dry showed approximately 4.2% weight lossfrom 35-115° C. by TG. The weight loss corresponds with a broadendotherm at approximately 57° C. in the DSC, likely indicative ofsolvent loss. An additional endotherm at approximately 204° C. in theDSC thermogram is ascribed to a melt. Proton NMR spectrum showed nopresence of organic solvent in the proton spectrum of Form ι-dry.

Rifaximin (quantity unmeasured) was placed in a clean vial. The vial wascovered with perforated aluminum foil and placed in a vacuum oven set at23° C. and 8-30 in Hg. After approximately 15 hours, the sample wasremoved from the vacuum oven and submitted for XRPD analysis.

After 3 months and 1 week of storage at ambient conditions, the samplewas submitted for XRPD analysis.

Rifaximin (quantity unmeasured) was placed in a clean vial and allowedto air-dry at ambient conditions. After approximately 3 hours the sampleappeared dry by perturbation with a spatula and was submitted for XRPDanalysis. The sample was stored at ambient conditions for approximately4 months and again analyzed by XRPD.

Form ι-dry was exposed to ethanol vapor at an initial relative vaporpressure of 0.45 decreasing to 0.05 in 0.1 increments. The materialdemonstrated a percent weight gain of approximately 10.3% after 10minutes at 0.45 relative vapor pressure, equivalent to two moles ofethanol. The material lost 1.47% of the gained weight (approximately0.25 mole ethanol) on the desorption curve from 0.45 to 0.05 relativepressure over 33 minutes. XRPD analysis of the sample after DVS analysisshowed a form eta.

Form ι-dry was exposed to ethanol vapor with a one step for saturationat 0.45 relative pressure of ethanol. The material demonstrated a 10.3%weight gain (equivalent to 2 moles of ethanol). XRPD analysis of thesample after DVS analysis showed Form ι.

Rifaximin (150 μL) was placed in a clean vial and placed in the freezer(−10 to −25° C.). After 57 days wet, birefringent red orange blades werenoted as individual crystals and spherulites and submitted for XRPDanalysis.

Rifaximin (quantity unmeasured, both in capillary and bulk) was placedin a jar containing a saturated salt solution to maintain a relativehumidity of 97% RH (saturated salt solution of potassium sulfate inwater). After 38 days the sample was analyzed by XRPD.

Methods of Preparation for Rifaximin Form Iota (ι)

Rifaximin (0.0294 g) was dissolved in ethanol (100 μL) resulting in aclear red solution. A red precipitate spontaneously occurred in lessthan 5 minutes. The vial was capped and left at ambient conditions. Wetred-orange birefringent fine needles were packed in a capillary andsubmitted for XRPD analysis. The remainder of the sample was allowed toair-dry. After less than one hour, the material appeared dry. Finered-orange needles exhibiting partial birefringence were submitted forXRPD.

Rifaximin (0.0996 g) was dissolved in methanol (300 μL) with sonicationresulting in a clear red solution. A portion of the solution (150 μL)was removed for another experiment. The vial was then capped andrefrigerated (2-8° C.) for 3 days. A clear red solution was noted andthe sample was transferred to the freezer (−10 to −25° C.). Wet,birefringent orange-red solids with dendritic formations were notedafter 20 days. The sample was transferred to the refrigerator (2-8° C.)and submitted for XRPD.

Sample was analyzed by DSC, TGA, DVS, ¹H NMR, FT-IR and hotstagemicroscopy approximately one month later.

Rifaximin (Form ζ (not refined), quantity unmeasured) was transferred toa clean vial and allowed to air-dry at ambient conditions. Afterapproximately 3 hours the sample appeared dry by touch with a spatulaand was submitted for XRPD analysis.

Form ι dry was exposed to ethanol vapor with a one step for saturationat 0.45 relative pressure of ethanol. The material demonstrated a 10.3%weight gain (equivalent to 2 moles of ethanol). XRPD analysis of thesample after DVS analysis showed Form ι.

Rifaximin (Form ζ, quantity unmeasured) was transferred to a clean vialand allowed to air-dry at ambient conditions. After approximately 3hours the sample appeared dry by touch with a spatula and was submittedfor XRPD analysis.

Rifaximin (0.1004 g) was dissolved in ethanol (340 μL) using a vortexmixer and spatula. A dark red solution was obtained and yielded anorange red precipitate after 5 min. Tiny birefringent needles weresubmitted wet for XRPD analysis. Form ζ on first analysis Form eta uponre-analysis. The sample was analyzed again after 3 months and 7 days ofstorage at ambient conditions.

Rifaximin (0.0284 g) was dissolved in ethanol (100 μL) resulting in aclear red solution (Nov. 7, 2008). A red precipitate spontaneouslyoccurred in less than 5 minutes. The vial was capped and left at ambientconditions. Wet red-orange birefringent fine needles were packed in acapillary and submitted for XRPD analysis. The remainder of the samplewas allowed to air-dry. After less than one hour, the material appeareddry. Fine red-orange needles exhibiting partial birefringence weresubmitted for XRPD.

Rifaximin (0.0996 g) was dissolved in methanol (300 μL) with sonicationresulting in a clear red solution. A portion of the solution (150 μL)was removed for another experiment. The vial was then capped andrefrigerated (2-8° C.) for 3 days. A clear red solution was noted andthe sample was transferred to the freezer (−10 to −25° C.). Wet,birefringent orange-red solids with dendritic formations were notedafter 20 days. The sample was transferred to the refrigerator (2-8° C.)and submitted for XRPD.

Rifaximin (0.1004 g) was dissolved in ethanol (340 μL) using a vortexmixer and spatula. A dark red solution was obtained and yielded anorange red precipitate after 5 min. Tiny birefringent needles weresubmitted wet for XRPD analysis. The sample was analyzed again after 3months and 7 days of storage at ambient conditions (a form eta). Thissample was Form ζ on first analysis and then Form eta upon re-analysis.

Rifaximin (0.0996 g) was dissolved in methanol (300 μL) with sonicationresulting in a clear red solution. A portion of the solution (150 μL)was removed for another experiment. The vial was then capped andrefrigerated (2-8° C.) for 3 days. A clear red solution was noted andthe sample was transferred to the freezer (−10 to −25° C.). Wet,birefringent orange-red solids with dendritic formations were notedafter 20 days. The sample was transferred to the refrigerator (2-8° C.)and submitted for XRPD.

Rifaximin (0.0996 g) was dissolved in methanol (300 μL) with sonicationresulting in a clear red solution. A portion of the solution (150 μL)was removed for another experiment. The vial was then capped andrefrigerated (2-8° C.) for 3 days. A clear red solution was noted andthe sample was transferred to the freezer (−10 to −25° C.). Wet,birefringent orange-red solids with dendritic formations were notedafter 20 days. The sample was transferred to the refrigerator (2-8° C.)and submitted for XRPD.

of Preparation for Rifaximin Form Eta

Rifaximin (0.1004 g) was dissolved in ethanol (340 μL) using a vortexmixer and spatula. A dark red solution was obtained and yielded anorange red precipitate after 5 min. Tiny birefringent needles weresubmitted wet for XRPD analysis. Form ζ on first analysis Form eta uponre-analysis. The sample was analyzed again after 3 months and 7 days ofstorage at ambient conditions.

Methods of Preparation for Rifaximin Form Zeta (ζ)

Rifaximin (265 mg) was combined with ethanol (1 mL) with shaking andsonication. The sample was slurried at ambient temperature on a shakerblock for 3 days. Solvent was removed by decantation and orangefragments exhibiting birefringence and extinction were analyzed damp byXRPD.

Rifaximin (200 mg) was combined with ethanol (1 mL) and water (20 μL)with shaking and sonication. The sample was slurried at ambienttemperature on a shaker block for 3 days. Solvent was removed bydecantation and orange irregular fragments exhibiting birefringence andextinction were analyzed damp by XRPD.

Rifaximin (256 mg) was combined with ethanol (1 mL) and water (100 μL)with shaking and sonication. The sample was slurried at ambienttemperature on a shaker block for 3 days. Solvent was removed bydecantation and orange irregular fragments exhibiting birefringence andextinction were stored refrigerated (2-8° C.) and analyzed damp by XRPD.

Rifaximin (256 mg) was combined with ethanol (1 mL) and water (100 μL)with shaking and sonication. The sample was slurried at ambienttemperature on a shaker block for 3 days. Solvent was removed bydecantation and orange irregular fragments exhibiting birefringence andextinction were stored refrigerated (2-8° C.) and analyzed damp by XRPD.After 3 weeks refrigerated storage the sample was analyzed by XRPD.

Rifaximin (353 mg) was combined with ethanol (1 mL) and water (0.25 mL)with shaking and sonication. The sample was heated on a hot plate (settemperature 68° C.) resulting in a clear orange solution. Heating wasdiscontinued and the vial allowed to cool to ambient temperature on thehot plate. After 3 days the clear solution was placed in therefrigerator (2-8° C.). A clear solution was noted after 2 days and thesample seeded with rifaximin. One day later orange needles exhibitingbirefringence and extinction were collected by filtration. The filtercake was submitted for XRPD analysis without further drying.

Rifaximin (130 mg) was combined with ethanol (4 mL) with shaking. Theresulting clear solution was filtered through a 0.2 μm nylon filter. Thesolvent was allowed to evaporate slowly. Six days later orange needlesexhibiting birefringence and extinction were collected by filtration.The filter cake was submitted for XRPD analysis without further drying.

Rifaximin (404.5 mg) was combined with ethanol (2.0 mL) and water (0.5mL). The vial was capped and the damp solids placed in the refrigerator(2-8° C.). Solids were analyzed damp by XRPD.

Rifaximin (0.0960 g) was combined with methanol (300 μL) withsonication. The resulting clear solution was capped and left at ambienttemperature. A red precipitate consisting of birefringent blades andneedles was observed after one day. After an additional day, the entiresolution crystallized and damp crystals were noted. The sample wasstored refrigerated.

Rifaximin (0.1004 g) was dissolved in ethanol (340 μL) using a vortexmixer. Dissolution was also facilitated using a spatula resulting in adark red solution. After approximately 5 minutes an orange redprecipitate was noted. Tiny needles exhibiting birefringence wereanalyzed by XRPD while wet.

Rifaximin (508 mg) was combined with ethanol (1.3 mL) and heated on ahot plate (set point at 70° C.). Water (0.58 mL) was added to the clearsolution and heating was continued. A clear brown solution was obtained.The vial was placed in an ice-water bath for approximately 3 hours andthen kept at ambient temperature overnight. A portion of the sample waspacked into a 1 mm glass capillary and analyzed by XRPD.

Rifaximin (503 mg) was combined with ethanol (1.3 mL) and heated on ahot plate (set point at 70° C.). Water (0.58 mL) was added to the clearsolution and heating was continued for approximately 5 minutes. A clearbrown solution was obtained. The sample was cooled at 3° C./hour from 70to 20° C. (instrument set point). After one day, a portion of the samplewas packed into a 1 mm glass capillary and analyzed by XRPD.

Rifaximin (402 mg) was combined with ethanol (2.0 mL) and water (0.5mL). The vial was capped and the slurry placed on a shaker block atambient temperature. After approximately 5 hours a portion of the samplewas packed into a 1 mm glass capillary and analyzed by XRPD.

Rifaximin (0.1004 g) was dissolved in ethanol (340 μL) using a vortexmixer and spatula. A dark red solution was obtained and yielded anorange red precipitate after 5 min. Tiny birefringent needles weresubmitted wet for XRPD analysis. The sample was analyzed again after 3months and 7 days of storage at ambient conditions. This sample was ζ onfirst analysis and Form eta upon re-analysis.

Rifaximin (0.1004 g) was dissolved in ethanol (340 μL) using a vortexmixer and spatula. A dark red solution was obtained and yielded anorange red precipitate after 5 min. Tiny birefringent needles weresubmitted wet for XRPD analysis. This sample was ζ on first analysis andForm eta upon re-analysis.

The sample was analyzed again after 3 months and 7 days of storage atambient conditions (a form eta). Rifaximin (0.1004 g) was dissolved inethanol (340 μL) using a vortex mixer and spatula. A dark red solutionwas obtained and yielded an orange red precipitate after 5 min. Tinybirefringent needles were submitted wet for XRPD analysis. Form Zeta onfirst analysis Form eta upon re-analysis. The sample was analyzed againafter 3 months and 7 days of storage at ambient conditions.

Methods of Preparation for Rifaximin Form B

Rifaximin (268 mg) was combined with ethanol (1 mL) and water (1 mL)with shaking and sonication. The sample was heated on a hot plate (settemperature 68° C.) resulting in a clear orange solution. Heating wasdiscontinued and the vial allowed to cool to ambient temperature on thehot plate. After 3 days, a small portion of solids and solution werepacked in a 1 mm glass capillary was submitted for XRPD analysis.

Rifaximin (268 mg) was combined with ethanol (1 mL) and water (1 mL)with shaking and sonication. The sample was heated on a hot plate (settemperature 68° C.) resulting in a clear orange solution. Heating wasdiscontinued and the vial allowed to cool to ambient temperature on thehot plate. After 3 days, a small portion of solids and solution werepacked in a 1 mm glass capillary was submitted for XRPD analysis. Solidswere collected from the remaining sample by decantation of solvent. Thesolids were air dried. Orange blades exhibiting birefringence andextinction were analyzed by XRPD, DSC and TGA.

Rifaximin was slurried on a shaker block at ambient temperature for 2days. A portion of sample in solution was packed capillary for analysisby XRPD.

Rifaximin (201 mg) was combined dissolved in ethanol (2 mL). The samplewas heated on a hot plate (instrument set point 85° C.) resulting in aclear orange solution. Water (2.0 mL) was added and the solution heatedfor an additional 5 minutes (approximate time). The clear solution wascooled at 5° C./hour from approximately 80-20° C.). After one day largeorange blades exhibiting birefringence and extinction were observed andthe sample was analyzed wet by XRPD. The sample was also submitted forsingle crystal structure determination.

Rifaximin was returned from single crystal structure analysis insolution. A small portion of solids and solution were packed in acapillary for XRPD analysis.

Rifaximin (110 mg) was combined with ethanol (4.0 mL) and heated on ahotplate (instrument set point at 80° C.). The clear solution wasfiltered through a 0.2 um nylon filter. The filtrated was heated(instrument set point at 80° C.) and water (6.0 mL) was added drop wiseresulting in a slightly cloudy solution. Heating was discontinued andthe sample allowed to remain on the hotplate. A portion of the sampleand solvent was placed in a capillary for analysis by XRPD.

Rifaximin (501 mg) was combined with ethanol (1.3 mL) and heated on ahotplate (instrument set point at 75° C.). A clear solution wasobtained. Water (0.5 mL) was added and the solution was heated on thehotplate for approximately 5 minutes. (instrument set point at 75° C.).Heating was discontinued and the sample cooled at a rate of 3° C./minfrom 70-20° C. (instrument set point). After 3 days a small portion ofsolids and solution were packed into a capillary for XRPD analysis.

Rifaximin (1.1209 g) was spread evenly in a petri dish. The petri dishplaced in a jar containing a saturated salt solution in order tomaintain a relative humidity of 84%. After 2 days, the solids wereremoved from the chamber and placed in a vial. The sample was analyzedby XRPD 12 days later.

Form B:

Rifaximin (0.0266 g) was combined with heptane (20.0 mL) withsonication. The sample was slurried at ambient temperature on an orbitalshaker (150 rpm). After 3 days the sample noted as completely dried andcontained solids exhibiting a morphology similar to broken glass.Birefringence was not observed. The sample was analyzed by XRPD.

Rifaximin (0.0266 g Lot) was combined with heptane (20.0 mL) withsonication. The sample was slurried at ambient temperature on an orbitalshaker (150 rpm). After 3 days the sample noted as completely dried andcontained solids exhibiting a morphology similar to broken glass.Birefringence was not observed. The sample was analyzed by XRPD.

Rifaximin (0.0288 g) was combined with acetone/water (1/1 v/v, 6.0 mL)with sonication resulting in a clear solution. The solution was filteredthrough a 0.2 um filter into a clean vial. The vial was left uncappedand solvent allowed to evaporate under ambient conditions. Four dayslater, orange, birefringent irregular plates were collected by vacuumfiltration and dried under reduced pressure for approximately 3 minutes.

Rifaximin (0.0288 g) was combined with acetone/water (1/1 v/v, 6.0 mL)with sonication resulting in a clear solution. The solution was filteredthrough a 0.2 um filter into a clean vial. The vial was left uncappedand solvent allowed to evaporate under ambient conditions. Four dayslater, orange, birefringent irregular plates were collected by vacuumfiltration and dried under reduced pressure for approximately 3 minutes.

Rifaximin (0.5351 g) was transferred to a vial containing IPA (2.97 mL)and water (30 μL) resulting in a sticky paste. The vial was capped andstored at ambient temperature. Tiny orange particles exhibiting partialbirefringence were noted after one day. Solids were collected by vacuumfiltration, air dried under reduced pressure for approximately 3 minutesand transferred to a clean vial. The sample was analyzed by XRPD.

Rifaximin (0.5281 g) was transferred to a vial containing IPA (2.91 mL)and water (90 μL) resulting in a sticky paste. The vial was capped andstored at ambient temperature. Tiny orange particles exhibiting partialbirefringence were noted after one day. Solids were collected by vacuumfiltration, air dried under reduced pressure for approximately 7 minutesand transferred to a clean vial. The sample was analyzed by XRPD.

Instrumental Parameters

All analyses were performed at ambient temperature unless otherwisespecified in the parameters.

X-Ray Powder Diffraction (XRPD)

Inel

X-ray powder diffraction analyses were performed using an Inel XRG-3000X-ray powder diffractometers with Cu Kα radiation. The Inel XRG-3000diffractometer is equipped with a CPS (Curved Position Sensitive)detector with a 2θ range of 120°. Real time data were collected usingCu—Kα radiation starting at approximately 4° 2θ at a resolution of 0.03°2θ. The tube voltage and amperage were set to 40 kV and 30 mA,respectively. The monochromator slit was set at 5 mm by 160 μm. Thepattern is displayed from 2.5-40° 2θ. Samples were prepared for analysisby packing them into thin-walled glass capillaries. Each capillary wasmounted onto a goniometer head that is motorized to permit spinning ofthe capillary during data acquisition. The samples were analyzed for 5min. Instrument calibration was performed using a silicon referencestandard.

Thermal Analyses

Differential Scanning Calorimetry (DSC)

Differential scanning calorimetry (DSC) was performed using a TAInstruments differential scanning calorimeter 2920. The sample wasplaced into an aluminum DSC pan, and the weight accurately recorded. Thepan was covered with a lid and then crimped or left uncrimped. Thesample cell was equilibrated at 25° C. and heated under a nitrogen purgeat a rate of 10° C./min, up to a final temperature of 350° C. Indiummetal was used as the calibration standard. Reported temperatures are atthe transition maxima.

DSC was performed using a TA Instruments Q2000 differential scanningcalorimeter. Temperature calibration was performed using NIST traceableindium metal. The sample was placed into an aluminum DSC pan, and theweight was accurately recorded. The pan was covered with a lid, and thelid was crimped. A weighed, crimped aluminum pan was placed on thereference side of the cell. The sample cell was equilibrated at 25° C.and heated under a nitrogen purge at a rate of 10° C./minute, up to afinal temperature of 250° C. Reported temperatures are at the transitionmaxima.

Thermogravimetric (TG) Analyses

Thermogravimetric (TG) analyses were performed using a TA Instruments2950 thermogravimetric analyzer. Each sample was placed in an aluminumsample pan and inserted into the TG furnace. The furnace was starteddirectly from ambient temperature, then heated under nitrogen at a rateof 10° C./min, up to a final temperature of 350° C. Nickel and Alumel™were used as the calibration standards.

Dynamic Vapor Sorption (DVS)

Dynamic vapor sorption (DVS) data were collected on a VTI SGA-100 VaporSorption Analyzer. NaCl and PVP were used as calibration standards.Samples were not dried prior to analysis. Adsorption and desorption datawere collected over a range from 5 to 95% RH at 10% RH increments undera nitrogen purge. The equilibrium criterion used for analysis was lessthan 0.0100% weight change in 5 minutes with a maximum equilibrationtime of 3 hours. Data were not corrected for the initial moisturecontent of the samples.

Solution 1D 1H NMR Spectroscopy

The solution NMR spectra were acquired with a Varian UNITYINOVA-400spectrometer. The samples were prepared by dissolving approximately 4-8mg in acetone-d6 or methanol-d4. The data acquisition parameters aredisplayed in the first plot of the spectrum in the Data section of thisreport

Infrared Spectroscopy (IR)

IR spectra were acquired on Magna-IR 860® Fourier transform infrared(FT-IR) spectrophotometer (Thermo Nicolet) equipped with an Ever-Glomid/far IR source, an extended range potassium bromide (KBr)beamsplitter, and a deuterated triglycine sulfate (DTGS) detector.Wavelength verification was performed using NIST SRM 1921b(polystyrene). An attenuated total reflectance (ATR) accessory(Thunderdome™, Thermo Spectra-Tech), with a germanium (Ge) crystal wasused for data acquisition. Each spectrum represents 256 co-added scanscollected at a spectral resolution of 4 cm⁻¹. A background data set wasacquired with a clean Ge crystal. A Log 1/R(R=reflectance) spectrum wasobtained by taking a ratio of these two data sets against each other.

Hot Stage Microscopy

Hot stage microscopy was performed using a Linkam hot stage (model FTIR600) mounted on a Leica DM LP microscope equipped with a SPOT Insight™color digital camera. Temperature calibrations were performed using USPmelting point standards. The camera is white balanced. Samples wereplaced on a cover glass, and a second cover glass was placed on top ofthe sample. As the stage was heated, each sample was visually observedusing a 20×0.40 N.A. objective with crossed polarizers or without toppolarizer, and a first order red compensator. Images were captured usingSPOT Advance software (v. 4.5.9).

XRPD Data and Indexing Results

The Topas refinement method used to determine the DP value for eachmeasured XRPD data file.

Topas was operated in a mixture plus unit cell refinement mode ratherthan the usual Rietveld mode. In this limited refinement mode, theinitial refinement pass was used to estimate the phase compositionrepresent by the data file under analysis. Many of the measured XRPDdata sets represent mixtures of various rifaximin phases which wereremoved to allow analysis of the pure phases.

For the remaining data sets judged to represent pure phases, the unitcell parameters of the corresponding phase model in Topas were allowedto vary along with an angular offset and sample displacement parameter.The unit cell parameters resulting from the best fit to the measureddata were used to determine the DP (dimensionless product) valuecorresponding to that data set.

Topas Phase Models

Topas is a Rietveld refinement package that has XRPD pattern fittingcapabilities. Each of the crystalline phases (forms) that Topas canmodel must first be loaded as an effective crystal structure using CIFfiles. The effective crystal structure for each crystalline form wasdetermined using a measured reference pattern for that phase and anapproximate starting structure. For the forms with single crystalstructures, the CIF files corresponding to those crystal structures wereused as the starting structures (usually the single crystal structuresare determined at low temperatures, which require unit cell refinementto correctly describe a powder pattern measured under ambientconditions). For forms without known crystal structures, an approximatestarting structure was derived from the closest matching known structureand an index solution to the powder pattern. The indexing was performedusing Dicvol v4.0. Some XRPD reference patterns did not yield an indexsolution due to the lack of well defined free standing diffractionpeaks. For these patterns, extensive refinement of the known crystalstructures was required to achieve a reasonable effective crystalstructure.

The effective crystal structure is not a solution to the actual crystalstructure of a form but is a structural model that provides a good fitto the measured XRPD reference pattern for that form.

Topas Mixture Refinement

Many of the XRPD data sets initially grouped as potentially representingpure phase material actually represented mixtures. To isolate only thepure phase data sets for subsequent DP analysis, Topas was initiallyconfigured with an ensemble of effective crystal structures representingthe potential mixtures. During the first refinement pass, only theconcentration of the individual phases (and some general scale actors)were allowed to refine. If the resulting best fit to the measured datagave a primary phase contribution of <70%, the data was rejected fromthe pure phase cluster and flagged as potentially representing amixture.

Topas Unit Cell Refinement

XRPD data sets representing pure phase material were modeled in Topasusing unit cell refinement of the corresponding effective crystalstructure. Along with the unit cell parameters (a, b, c, alpha, beta,gamma), an instrument offset parameter and sample displacement parameterwere refined. The resulting best fit unit cell was exported as an INPfile.

Characteristic peaks of Forms ι, ι-dry, ζ, and B that differentiate onecrystalline polymorph from another crystalline form are shown below inTable_. Characteristic peaks are determined by evaluating which peaksare present in one crystalline form of a compound against all otherknown crystalline form of that compound to within ±0.15° 2θ. Somecrystalline forms do not exhibit a characteristic peak, however, whencombined with other peak(s), the set of peaks differentiate thecrystalline form from other crystalline forms.

Shown below are Tables with peak lists for forms described herein. Fewerthan the described peaks, as listed above are identifying for the forms.A selection of peaks, from between 2-10 peaks could be identifying for aparticular form.

TABLE 1 Characteristic XRPD peak and peak sets of each crystalline formof rifaximin Form Iota Form Iota dry^(y) dry' Form Iota Form Zeta Form B6.045 6.165 5.495  4.69 ± 0.15 5.24 ± 0.15 7.905 7.925 5.885  7.63 ±0.15 6.84 ± 0.15 8.925 8.895 7.865 12.52 ± 0.15 7.74 ± 0.15 9.495 9.5559.035 13.87 ± 0.15 8.71 ± 0.15 12.765 12.805 12.665 10.16 ± 0.15  14.14514.255 13.895 12.21 ± 0.15 

TABLE 2 Peak List for Iota dry Relative Intensity Row °2θ (%) 1 6.04 ±0.15 80 2 7.90 ± 0.15 100 3 8.92 ± 0.15 59 4 9.49 ± 0.15 54 5 12.76 ±0.15  61 6 14.14 ± 0.15  53 a. Unique peak clusters at +/− 0.15 °2θmatching window against all phases except iota dry (prime) b.Doublets 1) 1 + 3 and 2) 3 + 6 c. Triplets - none d. Iota dry isdistinguishable from Iota's' but requires a narrower error window of +/−0.1

TABLE 3 Peak List for Iota dry' Relative Intensity Row °2θ (%) 1 6.16 ±0.15 99.6 2 7.92 ± 0.15 100 3 8.89 ± 0.15 52.2 4 9.55 ± 0.15 57.2 512.80 ± 0.15  56.2 6 14.25 ± 0.15  57.3 a. Unique peak clusters at +/−0.15 °2θ matching window against all phases except iota dry b.Doublets - none c. Triplets 1) 1 + 2 + 6 and 2) 1 + 3 + 6 and 3) 2 + 4 +6 d. Iota's dry' is distinguishable from Iota's dry with a +/− errorwindrow.

TABLE 4 Peak List for Iota Relative Intensity Row °2θ (%) 1 5.49 ± 0.1570.22 2 5.88 ± 0.15 67.46 3 7.86 ± 0.15 100 4 9.03 ± 0.15 57.61 4 12.66± 0.15  62.17 6 13.89 ± 0.15  54.4 a. Unique peak clusters at +/− 0.15°2θ matching window against all phases b. Doublets - none c. Triplets 1)1 + 2 + 4 and 2) 1 + 2 + 6 and 3) 2 + 4 + 5 and 4) 2 + 4 + 6

TABLE 5 Peak List for Zeta Relative Intensity Row °2θ (%) 1 4.69 100 27.63 63.48 3 12.52 24.68 4 13.87 24.81 a. Unique peak clusters at +/−0.15 °2θ matching window against all phases b. Doublets 1) 1 + 2 c.Triplets 1) 2 + 3 + 4 d. Matching against patented forms (α, β, δ, γ,ε) - no overlap

TABLE 6 Peak List for Form B Relative Intensity Row °2θ (%) 1 5.24 100.02 6.84 79.9 3 7.74 96.9 4 8.71 39.4 5 10.16 73.2 6 12.21 38.6 a. Uniquepeak clusters at +/− 0.15 °2θ matching window against all phases b.Doublets 1) 1 + 5 c. Triplets 1) 2 + 3 + 4 and 2) 1 + 3 + 4 and 3) 1 +4 + 6 and 4) 2 + 3 + 4 and 5) 2 + 3 + 5 and 6) 2 + 4 + 5 and 7) 4 + 5 +6 d. Matching against patented forms (α, β, δ, γ, ε) - no overlap

Incorporated by Reference

The contents of all references, patents, pending patent applications andpublished patents, cited throughout this application are herebyexpressly incorporated by reference.

EQUIVALENTS

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

1. Polymorphic Form ζ, Form η, Form ι, Form ι-dry, Form ι-dry′, or FormB of rifaximin.
 2. The polymorph Form ζ of claim 1, wherein thepolymorph exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)comprising 4.69, 7.63, 12.52, 13.87.
 3. The polymorph Form ζ ofrifaximin of claim 1, comprising an XRPD pattern as substantiallydepicted in FIG. 4 or FIG. 15 wherein peaks in the XRPD patterns have avariation of +/−0.2 theta.
 4. The polymorph Form η of claim 1, whereinthe polymorph exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.20 degree θ)comprising 6.1, 7.3, and 7.5 degrees 2-θ; or 6.1, 7.3, and 7.9 degrees2-θ; 5.3, 6.1, 7.3, 7.5, 8.8, and 12.7 degrees 2-θ.
 5. The polymorphForm ι of claim 1, wherein the polymorph exhibits an X-ray powderdiffraction pattern having characteristic peaks expressed in degrees 2θ(+/−0.20 degree θ) comprising 5.49, 5.88, 7.86, 9.03, 12.66, and 13.89.6. The polymorph Form ι of claim 1, wherein the polymorph exhibits anX-ray powder diffraction pattern having characteristic peaks expressedin degrees 2θ (+/−0.20 degree θ) comprising 5.9; 7.9; 9.0; or 12.7;13.9; 14.9; or 5.9; 7.9; 12.7; or 5.9; 9.0; 12.7; or 5.9; 13.9;
 14. 9;or 5.9; 7.9; 14.9; or 9.0; 12.7; 14.9; or 5.9; 7.9; 9.0; 14.9; or 5.9;7.9; 9.0; 12.7; or 5.9; 7.9; 9.0; 12.7; 13.9; 14.9.
 7. The polymorphForm ι of rifaximin of claim 1, comprising an XRPD pattern assubstantially depicted in FIG. 3 or FIG. 9 wherein peaks in the XRPDpatterns have a variation of +/−0.2 theta.
 8. The polymorph Form ι ofrifaximin of claim 1, comprising thermal data as substantially depictedin FIG. 10 or proton NMR spectrum as substantially depicted in FIG. 12or vapor data as substantially depicted in FIG. 11 or FT-IR spectrum assubstantially depicted in FIG.
 13. 9. The polymorph Form ι of claim 1,wherein the Form ι is formulated into a pharmaceutically acceptabledosage form.
 10. The polymorph From ι-dry of claim 1, wherein thepolymorph exhibits an X-ray powder diffraction pattern havingcharacteristic peaks expressed in degrees 2θ (+/−0.10 degree θ)comprising 6.04, 7.90, 8.92, 9.49, 12.76, and 14.14.
 11. The polymorphForm ι-dry of rifaximin of claim 1, comprising an XRPD pattern assubstantially depicted in FIG. 1 or FIG. 6 or thermal data assubstantially depicted in FIG.
 7. 12. The polymorph From ι-dry of claim1, wherein the Form ι-dry is formulated into a pharmaceuticallyacceptable dosage form.
 13. The polymorph From ι-dry′ of claim 1,wherein the polymorph exhibits an X-ray powder diffraction patternhaving characteristic peaks expressed in degrees 2θ (+/−0.15 degree θ)comprising 6.16, 7.92, 8.89, 9.55, 12.80, and 14.25.
 14. The polymorphForm ι-dry′ of rifaximin of claim 1, comprising an XRPD pattern assubstantially depicted in FIG. 2 or FIG. 8 wherein peaks in the XRPDpatterns have a variation of +/−0.15 theta.
 15. The polymorph Fromι-dry′ of claim 1, wherein the Form ι-dry′ is formulated into apharmaceutically acceptable dosage form.
 16. The polymorph From B ofclaim 1, wherein the polymorph exhibits an X-ray powder diffractionpattern having characteristic peaks expressed in degrees 2θ (+/−0.15degree θ) comprising 5.24, 6.84, 7.74, 8.71, 10.16, and 12.21.
 17. Thepolymorph Form B of claim 1, comprising an XRPD pattern as substantiallydepicted in FIG. 6 wherein peaks in the XRPD patterns have a variationof +/−0.15 theta or having DSC or TGA thermograms as substantiallydepicted in FIG.
 17. 18. The polymorphs of claim 1, wherein thepolymorphs comprise from between about 50 to about 100% purepolymorphous forms before or after formulation.
 19. The polymorphs ofclaim 1, wherein the polymorphs comprise from between about 75 to about100% pure polymorphous forms before or after formulation.
 20. Apharmaceutical dosage form comprising one or more of polymorphic Form ζ,Form η, Form ι, Form ι-dry, Form ι-dry′, or Form B of rifaximin ormixtures thereof.